The physical and electronic properties of aluminum nitride (AlN) give it great potential for a wide variety of semiconductor applications. AlN has a wide energy bandgap (6.2 electron volts), high breakdown electric field and extremely high thermal conductivity. In fact, in Chow et. al Wide Bandgap Compound Semiconductors for Superior High Voltage Unipolar Power Devices (IEEE Transactions on Electron Devices, Vol. 41, No. 8, 1994) ranking all semiconductors materials, AlN is reported to have, excluding diamond, the highest figure of merit for unipolar power device performance.
In addition, the high thermal conductivity and high optical transmissivity (i.e., low optical density) of AlN make AlN an excellent candidate substrate material. Also, AlN is likely to be the optimum substrate for the growth of pseudo-binary inter metallic compounds such as Al.sub.0.8 In.sub.0.2 N which have extremely high figures of merit for semiconductor performance (up to 4,413,000 times silicon). Although AlN has extraordinary properties for a semiconductor material and has tremendous commercial potential, AlN based semiconductor devices have been limited by the unavailability of large, low defect AlN single crystals. In the most successful prior work, Slack and McNelly demonstrated a method for growing AlN single crystals via sublimation in AlN Single Crystals (Journal of Crystal Growth 42, 1977). However, the time required to grow a 12 mm by 4 mm crystal was approximately 150 hours. This growth rate of 0.08 mm per hour is too low to allow the commercial production of AlN single crystals.